Radio receiving set



1931- P. w. WILLANS ET AL 1,329,175

RADIO RECEiVING SET Filed Feb. 2. 1928 2 Sheets-Sheet 1 t- 1931- P. w. WILLANS ET AL 1,829,175

RADIO RECEIVING SET Filed Feb. 2. 1923 2 Sheets-Shea- 2 Patented Oct. 27, 1931 UNITED STATES PATENT -OFFICE PETER WILLIAM WILLANS, OF PATTISHALL, TOWOESTEIR, AND FREDERICK JOHN HENRY CHAIRMAN, OF BEDFORD, ENGLAND RADIO RECEIVING SET Application filed February 2, 1928, Serial No.

s relatively few turns.

One object of this invention is the provision of means in such apparatus for stabilizing the coupling coefiicient between the inductance, commonly called the leakage in- !(9 ductanoe, in the circuits connected to the said transformer windings.

Another is the provision of suitable transformers for use in such a para-tus the windings of which will have a re atively high inductive coupling and a relatively low mutual capacity.

Other objects and advantages will appear hereinafter.

In order that the invention may be the more clearly understood a receiving apparatus in accordance therewith will now be de scribed reference being made to the accompanying drawings, wherein:

Figure 1 is a diagrammatic representation of said receiving apparatus.

Figure 2 is a sectional view of a transformer structure comprised in said set.

Figure 3 is a sectional view to an enlarged scale of a. portion of another transformer structure comprised in said set.

Thus referring first to Figure 1 said apparatus comprises two high frequency aniplifying valves (11 and a2 and a detector valve d. The grid circuit of the valve (11 is supplied in the usual way from the aerial A through the medium of inductance coils c1 and 02. The plate circuit of said valve a1 is energized with the full voltage of the high tension battery B1 and includes in addition to the usual inductance coil 03 a choke hl. The grid circuit of the valve a2 is supplied in the usual wa from an inductance coil 04 coupled to said inductance coil 03. The plate circuit of the valve (12 which is energized with a selected proportion of the voltage of the battery B1 comprises,in addition to the primary of the low frequency transformer T, two chokes b2 and b3. The detector valve (1 is supplied by said transformer and supplies the telephones t in the manner 251,400, and in Great Britain July 21, 1927.

clearly shown, the plate circuit thereof being supplied with a still smaller proportion of the high tension voltage.

The coil 02 is coupled to a coil n1 and the coil 03 is coupled to a coil n2, and said coils 121 and n2 are connected in a closed circuit together with a capacity p. In this way capacita-tive coupling between the elements of the first stage of amplification is neu tralized as described in the specification of prior Letters Patent No. 1,637,924.

A reaction coil 7" is coupled to the coil 04 and has one end connected through a variable condenser to the plate and the other end connected to the filament of the valve a2 as shown. Said variable condenser is electrostatically screened from the aerial circuit.

The receiver is adapted for short wave reception and the three transformers constituted respectively by 02, n1; (:3, n2; and c4, 7' employ only a few turns. Therefore if the connecting leads of the windings of said transformers were arranged in the ordinary way the inductance of these connecting leads would tend to preponderate over the transformer effect to such an extent as seriously to diminish the coupling coefiicient between said transformer windings, thus causing instability which becomes more marked the shorter the wave length which is received.

In order to avoid this said connecting leads from the said transformer windings are brought out close to, and parallel with, each other so as to form loops of minimum area for each circuit. In this way the coupling coefiicient between said transformer windings (which is substantially equal to unity) is substantially undiminished.

More particularly the leads 1 and 2 of the circuit of the coil 62, 3 and 4 of the circuit of the coils n1, n2, 5 and dot the circuits of the coil 03, 7 and 8 and also 9, 10 and 11 of the circuit ofthe coil 1" are located close together as indicated.

The coils c2 and 111 are arranged in one structure on a common former and the coils c3, 04, W2 and '1' are also arranged in one structure on a common former. The former of these structures is illustrated in section in Figure 2, the latter in Figure 3. Said former structure comprises an insulating cylindrical former having its periphery grooved with a single helical groove 1 of V section. The coil all has wire of less cross sectional area than the coil 02 and is wound in this groove first, the coil 02 being wound in the same groove subsequently. By virtue of its small thickness the wire of the coil n1 rests substantially at the bottom of the groove and by virtue of its greater thiti-zness the wire of the coil 02 is supported by the sides of the groove a. little distance from the bottom and out of contact with the coil n. The two coils are thus clearly inductively coupled together.

As previously stated the two ends of each coil are brought out from the transformer parallel and close together. Thus as shown in Fig. 2 the two ends of the coil 02 are passed through the wall of the former at suitable points and are led close and parallel to one another to terminals m1 mounted close together at one end of said former. From these terminals the leads to the input to the valve (11 are taken close and parallel to one another.

The ends of the coil 921 are led in like manner I 0 terminals 1222 from which leads to the coil 012 are taken close and parallel to one another. 7

The structure of Figure comprises an insulating cylinder grooved with two helical grooves g2 and 3 which interleave one another as shown. The groove 92 supports both the windings c3 and 912 in the same way as the aforesaid groove 91 supports the windings 0.2 and a1, and in like manner the groove 93 supports the windings c4 and 1'. It is thus clear that the coils c3 and n2 are coupled together and that the coils at and 1 are coupled together. It will also be seen that the coils c3 and 0d are coupled together. but in order that the coils 922 and 2" shall not be coupled together one is wound at one end of the former only and the other is wound at the other end of the former. This arrangement accommodates itself quite conveniently to the electrical requirements as the number of turns required for the coils n2 and 9' is less than the number required for the coils c3 and 0d.

The ends of the four coils of Fig. 3 are led out to terminals close together in the same way as the ends of the two coils of Fig. 2.

lVhat we claim and desire to secure by Let ters Patent is 1. In a. radio receiving apparatus a transformer winding of relatively few turns and means completing a circuit therethrough, said means comprising connecting leads extending from said winding close to, and parallel with one another, whereby the area of the loop constituted by said circuit is reduced.

2. In a radio receiving apparatus a transformer winding of relatively few turns, a thermionic valve and means completing a circuit through said winding and certain of the elements of said valve, said means comprising connecting leads leaving said winding close to, and parallel with one another whereby the area of the loop constituted by said circuit is reduced.

3. In a. "radio receiving apparatus, two transformers of relatively few turns, a thermionic valve, a condenser means for completing a circuit through a winding of one of said transformers and the grid filament path of said valve, said means comprising connecting leads leaving said winding close to, and parallel with one another, means for completing circuit through a winding of the other transformer and the plate filament path of said valve, said means comprising connecting leads leaving said winding close to and parallel with one another, and means for completing circuit through the other winding of said transformer, the other winding of said latter transformer and said condenser, said means comprising connecting leads leaving said windings close to and parallel with one another. 3 f

In a radio receiving apparatus, a transformer of relatively few turns, a thermionic valve, means completing a circuit through one winding of said transformer and the grid :ilament path of said valve, said means comprising connecting leads leaving said winding close to and parallel with one another, and means connecting the other winding of said transformer between the filament and plate of said valve, whereby said winding acts as a. reaction coil.

5. In a radio receiving apparatus, a transformer of relatively few turns, the two windings of which lie in a common groove and are spaced apart by virtue of the shape of said groove, means completing acircuit through each of said windings, said means comprising connecting leads extending from said winding close to and parallel with one a11- other. 7

In witness whereof we affix our signatures.

PETER WILLIAM WILLANS. FREDERICK JOHN HENRY CHARMAN. 

